The long-term objective of this proposal is to gain a better understanding of the genetic mechanism underlying vertebrate eye formation. The eye is a frequent target of human inherited diseases. To address this problem, an understanding of the genetic regulatory networks required for normal eye formation is essential. We have discovered that eye formation requires the coordinated action of a group of transcriptional regulators expressed in the eye primordia (or eye field). These eye field transcription factors (EFTFs) are sufficient to transform primitive ectoderm to eye primordia and functional eyes. The goals of this study are to identify the transcripts specifically expressed in the eye primordia and determine the first genetic targets of the regulatory network driving eye formation. The specific aims are Aim 1: Genomics approach to identify transcripts expressed during eye primordia specification. We will first determine the gene expression profile of the eye primordia using microarray analysis. Next, we will compare the expression profiles of the endogenous eye primordia with that of EFTF-induced, in vitro produced, eye primorida to generate the first comprehensive profile of genes induced during early eye formation. Aim 2. Identify transcripts regulated by the eye primordia transcription factors. The transcription profiles for each EFTF will be determined using microarray analysis, quantitative PCR and in situ hybridization, to identify independently and coordinately regulated targets. The rationale for the proposed experiments is that the Xenopus transcriptosome required for eye formation will be a valuable tool for cross species comparisons, identification of new genes, and the generation of a preliminary map of the transcriptional network of eye formation. This network will also provide a foundation for systematic examination of new data and will help identify novel biological pathways requiring additional investigation. Identification of the genes and genetic pathways in the developing eye will provide a much-needed understanding of the genetic mechanisms underlying eye formation and provide a window into understanding and treating human blindness.